Hardin cites as an example for the tragedy of the commons:
" Picture a pasture open to all. It is to be expected that each herdsman will try to keep as many cattle as possible on the commons... As a rational being, each herdsman seeks to maximize his gain. Explicitly or implicitly, more or less consciously, he asks, "What is the utility to me of adding one more animal to my herd?" This utility has one negative and one positive component.
"1) The positive component is a function of the increment of one animal. Since the herdsman receives all the proceeds from the sale of the additional animal, the positive utility is nearly +1.
"2) The negative component is a function of the additional overgrazing created by one more animal. Since, however, the effects of overgrazing are shared by all the herdsmen, the negative utility for any particular decision-making herdsman is only a fraction of -1."
Hardin offers two alternative solutions, selling the pastures as private property or allocating the right to enter them, to this problem. However, allocating the right to enter the pastures would require that this allocation process be continually regulated on into the future, whereas simply selling the property would remove any need for making laws and regulations surrounding these pastures beyond the already existing property laws. Either solution would indeed solve the problem presented, but one is only more efficient.
Hardin then uses pollution as another example of the tragedy of the commons:
"In a reverse way, the tragedy of the commons reappears in problems of pollution. Here it is not a question of taking something out of the commons, but of putting something in--sewage, or chemical, radioactive, and heat wastes into water; noxious and dangerous fumes into the air, and distracting and unpleasant advertising signs into the line of sight. The calculations of utility are much the same as before. The rational man finds that his share of the cost of the wastes he discharges into the commons is less than the cost of purifying his wastes before releasing them. Since this is true for everyone, we are locked into a system of "fouling our own nest," so long as we behave only as independent, rational, free-enterprises."
Hardin's goes on to express the problem with human population growth:
"In a welfare state, how shall we deal with the family, the religion, the race, or the class (or indeed any distinguishable and cohesive group) that adopts overbreeding as a policy to secure its own aggrandizement (13)? To couple the concept of freedom to breed with the belief that everyone born has an equal right to the commons is to lock the world into a tragic course of action.
"Unfortunately this is just the course of action that is being pursued by the United Nations. In late 1967, some 30 nations agreed to the following (14):
"The Universal Declaration of Human Rights describes the family as the natural and fundamental unit of society. It follows that any choice and decision with regard to the size of the family must irrevocably rest with the family itself, and cannot be made by anyone else.
"It is painful to have to deny categorically the validity of this right; denying it, one feels as uncomfortable as a resident of Salem, Massachusetts, who denied the reality of witches in the 17th century."
Hardin ultimately bring up a coercive solution:
"We are willing to say "Consider bank-robbing... We are willing to say "Thou shalt not rob banks," without providing for exceptions. But temperance also can be created by coercion."
However, Hardin has missed an important point. Coercion against the bank-robber is only being used because the bank robber was using coercion himself. Coercion being used outside of punishing for others coercing only reduces the state to a bully, and should not be thought of an acceptable course of action.
"To say that we mutually agree to coercion is not to say that we are required to enjoy it, or even to pretend we enjoy it. Who enjoys taxes? We all grumble about them. But we accept compulsory taxes because we recognize that voluntary taxes would favor the conscienceless. We institute and (grumblingly) support taxes and other coercive devices to escape the horror of the commons."
This is almost true. In actuality, there are many people who do not accept paying compulsory taxes and do not pay their taxes. There is a small but vocal minority of people comprise primarily of libertarians who are actually for the abolition of taxes on the grounds that it is coercive.
Hardin commits the fallacy of believing that because everyone agrees coercion is good in this instance, that coercion can be used for good. But there was a time when the majority of people believed that skin color was a sound basis for determining a person's social caste. Just because a majority agree does not mean that something is or can be used as a means for achieving good, and if Hardin wants to use coercion to solve these problems he should find some moral ground for asserting that it can be good.